Aircraft engine repair tool and method for removal and installation of a mid turbine frame in an aircraft engine

ABSTRACT

An aircraft engine repair tool for installing and/or removing a mid turbine frame from a gas turbine engine is provided. The tool includes a stabilizer configured to support a shaft via a load path different from a load path provided by the mid turbine frame rotatably supporting the shaft about a rotation axis. The tool includes a holder attachable to the mid turbine frame, and a guide movably engageable with the shaft and attachable to the holder. The guide guides movement of the holder and of the mid turbine frame relative to the shaft along the rotation axis, and prevents movement of the holder and the mid turbine frame relative to the shaft transverse to the rotation axis when the mid turbine frame is released from the support structure and attached to the holder, and when the holder is attached to the guide.

TECHNICAL FIELD

The disclosure relates generally to aircraft engines, and moreparticularly to the assembly and disassembly of aircraft engines.

BACKGROUND

Some turbofan aircraft engines (e.g., gas turbine engines) have a midturbine frame located between a high-pressure turbine stage and alow-pressure turbine stage during operation of the gas turbine engine.The removal or installation of a mid turbine frame in a gas turbineengine, whether during initial assembly of the engine or duringmaintenance, is a time-consuming and expensive task that requiressignificant disassembly of the gas turbine engine in order to facilitateaccess and safe handling of the mid turbine frame. Improvement isdesirable.

SUMMARY

In one aspect, the disclosure describes an assembly comprising:

a gas turbine engine including a mid turbine frame located between afirst turbine rotor and a second turbine rotor in a turbine section ofthe gas turbine engine during operation of the gas turbine engine, themid turbine frame being releasably attached to a support structurewithin the gas turbine engine, the gas turbine engine including a shaftsupporting the first turbine rotor, the mid turbine frame rotatablysupporting the shaft relative to the support structure about a rotationaxis, the mid turbine frame defining a first load path between the shaftand the support structure, the second turbine rotor being uninstalledfrom the gas turbine engine; and

an aircraft engine repair tool for installing and/or removing the midturbine frame when the mid turbine frame is released from the supportstructure of the gas turbine engine, the aircraft engine repair toolincluding:

a stabilizer supporting the shaft via a second load path between theshaft and the support structure, the second load path being differentfrom the first load path;

a holder attached to the mid turbine frame; and

a guide movably engaged with the shaft and attached to the holder, theguide guiding movement of the holder and the mid turbine frame relativeto the shaft along the rotation axis, and preventing movement of theholder and the mid turbine frame relative to the shaft transverse to therotation axis when the mid turbine frame is released from the supportstructure.

In another aspect, the disclosure describes an aircraft engine repairtool for installing and/or removing a mid turbine frame from a gasturbine engine, the mid turbine frame being releasably attached to asupport structure of the gas turbine engine, the mid turbine framerotatably supporting a shaft relative to the support structure about arotation axis, the mid turbine frame defining a first load path betweenthe shaft and the support structure, the aircraft engine repair toolcomprising:

a stabilizer configured to support the shaft via a second load pathbetween the shaft and the support structure, the second load path beingdifferent from the first load path;

a holder attachable to the mid turbine frame; and

a guide movably engageable with the shaft and attachable to the holder,the guide guiding movement of the holder and the mid turbine framerelative to the shaft along the rotation axis and preventing movement ofthe holder and the mid turbine frame relative to the shaft transverse tothe rotation axis when the mid turbine frame is released from thesupport structure and attached to the holder, and when the holder isattached to the guide.

In a further aspect, the disclosure describes a method for installing amid turbine frame on a gas turbine engine, or removing the mid turbineframe from the gas turbine engine, the mid turbine frame being locatedbetween a first turbine rotor and a second turbine rotor in a turbinesection of the gas turbine engine during operation of the gas turbineengine, the mid turbine frame rotatably supporting a shaft about arotation axis and defining a first load path between the shaft and asupport structure of the gas turbine engine, the second turbine rotorbeing uninstalled from the gas turbine engine and the shaft supportingthe first turbine rotor, the method comprising:

supporting the shaft via a second load path between the shaft and thesupport structure of the gas turbine engine, the second load path beingdifferent from the first load path;

movably engaging the shaft with a guide and attaching the guide to aholder to permit movement of the holder relative to the shaft along therotation axis and prevent movement of the holder relative to the shafttransverse to the rotation axis;

with the mid turbine frame attached to the holder and the mid turbineframe released from the support structure of the gas turbine engine,moving the holder and the mid turbine frame together along the rotationaxis toward or away from an installed position of the mid turbine framein the support structure; and

after moving the holder and the mid turbine frame along the rotationaxis, either:

attaching the mid turbine frame to the support structure when the holderand the mid turbine frame have been moved toward the installed positionof the mid turbine frame; and

releasing the mid turbine frame from the support structure when theholder and the mid turbine frame have been moved away from the installedposition of the mid turbine frame.

Further details of these and other aspects of the subject matter of thisapplication will be apparent from the detailed description includedbelow and the drawings.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying drawings, in which:

FIG. 1 shows an axial cross-section view of a turbo-fan gas turbineengine including a mid turbine frame;

FIG. 2 shows the axial cross-section view of the turbo-fan gas turbineengine of FIG. 1 , with a low-pressure turbine stage being removedtherefrom;

FIG. 3 is a partially exploded, perspective view taken from a top,front, right side of components of an exemplary stabilizer of anaircraft engine repair tool;

FIG. 4 is an axial cross-section view of the components of thestabilizer of FIG. 3 , with a front case and bypass duct of the engineof FIG. 1 , and with a high-pressure shaft and mid turbine frame of theengine of FIG. 1 ;

FIG. 5 is a perspective view taken from a top, rear right side of agauge tool of the aircraft engine repair tool;

FIG. 6A is a perspective view of four support pins of the aircraftengine repair tool;

FIG. 6B is a perspective view of a cross-section of the engine of FIG. 1taken along cross-section line 6B-6B of FIG. 1 , with the support pinsof FIG. 6A attached to an inner casing of the engine of FIG. 1 ;

FIG. 7 is a perspective view taken from a top, rear, right side of aholder and a guide of the aircraft engine repair tool, with the holderbeing attached to an aft portion of the mid turbine frame of the engineof FIG. 1 , and with the gauge tool of FIG. 6 engaging the guide;

FIG. 8 is a perspective view taken from a top, rear, right side of theguide of FIG. 7 ;

FIG. 9 is a perspective view taken from a top, rear, right side of aninsert of the guide of FIG. 8 ;

FIG. 10 is a perspective view taken from a top, front, left side of theholder of FIG. 7 ;

FIG. 11 is a perspective view taken from a top, rear, right side of anextension frame for the holder of FIG. 7 ;

FIG. 12 is an axial cross-section view of components of the aircraftengine repair tool attached to the mid turbine frame of the engine ofFIG. 1 ;

FIG. 13 is an axial cross-section view of the engine of FIG. 1 , withthe aircraft engine repair tool moving the mid turbine frame away fromor toward an installed position of the mid turbine frame; and

FIG. 14 is a flowchart of a method for installing a mid turbine frame ona gas turbine engine, or removing the mid turbine frame from the gasturbine engine.

DETAILED DESCRIPTION

The following disclosure describes aircraft engine repair tools andmethods for installing a mid turbine frame in an aircraft (e.g., gasturbine) engine, or removing the mid turbine frame from the gas turbineengine with reduced disassembly of the gas turbine engine. The midturbine frame may be a structural component of the aircraft engine andmay be releasably attached to a support structure of the aircraftengine, such as an inner casing of the gas turbine engine. The midturbine frame may be located between a high-pressure turbine rotor andlow-pressure turbine rotor in a turbine section of the engine duringoperation of the engine. The gas turbine engine may further include ashaft supporting the high-pressure turbine rotor of the gas turbineengine. The mid turbine frame may rotatably support the shaft relativeto the support structure about a rotation axis. The mid turbine framemay define a load path between the shaft and the support structure.

In some embodiments, the aircraft engine repair tool described hereinmay include a stabilizer for supporting the shaft via a different(substitute) load path, a holder attachable to the mid turbine frame,and a guide for guiding the movement of the holder and the mid turbineframe relative to the shaft along the rotation axis. The movement of theholder together with the mid turbine frame along the rotation axis maybe guided by the guide so as to permit relatively accurate and stablemovement of the holder and mid turbine frame over a relatively longreach inside the gas turbine engine. The stability of the movement ofthe holder within the gas turbine engine provided by the guide may, insome embodiments, facilitate safe access and handling of the mid turbineframe without requiring significant disassembly of the gas turbineengine. Embodiments of the aircraft engine repair tools described hereinmay be suitable for use in the field for removable/installation of a midturbine frame in an aircraft-mounted engine (e.g., on wing).

The term “attached” as used herein may include both direct attachment(in which two elements that are attached to each other contact eachother) and indirect attachment (in which at least one additionalintermediate element is disposed between the two elements).

The term “connected” or “coupled” may include both direct connection orcoupling (in which two elements contact each other) and indirectconnection or coupling (in which at least one additional element islocated between the two elements).

Aspects of various embodiments are described through reference to theaccompanying drawings.

FIG. 1 illustrates a gas turbine engine 10 of a type preferably providedfor use in subsonic flight, generally comprising in serial flowcommunication a fan 12 through which ambient air is propelled, amultistage compressor 14 for pressurizing the air, a combustor 16 inwhich the compressed air is mixed with fuel and ignited for generatingan annular stream of hot combustion gases, and a turbine section 18 forextracting energy from the combustion gases. Engine 10 may includebypass duct 20 and core gas path 22 that are separated by inner casing24. Flow splitter 26 may be disposed at a forward end of inner casing24. Engine 10 may include fan case 28 inside which fan 12 is rotatablymounted. At a forward end 31 of engine 10, nose cone 30 may be disposedforward of fan 12 and releasably attached for common rotation with fan12.

Engine 10 may include bypass stator 34, which may be an airfoil-shapedstrut providing structural support within engine 10. At an aft end 36 ofengine 10, a turbine exhaust case 38 may be disposed rearward of turbinesection 18.

Engine 10 may be a dual spool gas turbine engine. Engine 10 may includelow-pressure shaft 32 to which fan 12, compressor boost module 39 andlow-pressure turbine stage 40 are drivingly coupled thereto. Compressorboost module 39 may be a compressor rotor assembly including one or moreinitial stages of compressor 14.

Engine 10 may include high-pressure shaft 42 to which high-pressureturbine stage 44 and high-pressure compressor 46 are drivingly coupledthereto. High-pressure turbine stage 44 may include a plurality ofturbine rotors 44 a. High-pressure compressor 46 may include a pluralityof compressor rotors 46 a. Low-pressure shaft 32 and high-pressure shaft42 may be mechanically uncoupled to permit separate rotation.Low-pressure shaft 32 and high-pressure shaft 42 may be mountedcoaxially for rotation about rotation axis R. As best seen in FIG. 1 ,low-pressure shaft 32 may extend inside high-pressure shaft 42. A radialgap 43 (FIG. 2 ) may be defined between low-pressure shaft 32 andhigh-pressure shaft 42.

Engine 10 may include a mid turbine frame 50, sometimes referred to asan “interturbine frame”, located between high-pressure turbine stage 44and low-pressure turbine stage 40. In some embodiments, mid turbineframe 50 may be of a type as disclosed in U.S. Pat. No. 8,061,969, whichis incorporated herein by reference. Mid turbine frame 50 may bereleasably attached (e.g., fastened) to inner casing 24. In someembodiments, mid turbine frame 50 could be releasably attached to othersupport structure(s) within engine 10. Mid turbine frame 50 may includebearing housing 52 (FIG. 4 ) to support one or more bearings rotatablysupporting shafts 32, 42 to rotate about the rotation axis R. Midturbine frame 50 may be a load bearing structure transferring loads fromshafts 32, 42 to inner casing 24 via load path L1 (FIG. 1 ). Mid turbineframe 50 may include inner ring 54 supporting bearing housing 52, andone or more struts 56 extending radially outwardly to outer ring 58.Outer ring 58 may be releasably attached to inner casing 24 using aplurality of fasteners accessible from aft end 36 of engine 10 whenlow-pressure turbine stage 40 and turbine exhaust case 38 are removedfrom engine 10. Load path L1 may thus include, without being limited to,bearing housing 52, strut(s) 56 and outer ring 58 of mid turbine frame50.

Referring to FIG. 2 , before installing and/or removing the mid turbineframe 50 from engine 10 using aircraft engine repair tool 60, turbineexhaust case 38 and low-pressure turbine stage 40 may be removed fromengine 10. As schematically shown in FIG. 2 , low-pressure turbine stage40 may be removed using low-pressure turbine stage support 62.Low-pressure turbine stage support 62 may include an interface 64adapted for attachment to an aft portion of the low-pressure turbinestage 40. Low-pressure turbine stage support 62 may further includeextension frame 64 a adapted to hold and position support 62 forattachment to low-pressure turbine stage 40 from aft end 36 of theengine 10 whilst leaving outer bypass duct 20 on the engine 10.Low-pressure turbine stage support 62 may be supported by (e.g.connected to) a suitable machinery mover 66 (schematically shown in FIG.2 ) such as a stand, wheeled cart, articulated arm or overhead supportfor example. As shown in FIG. 2 , machinery mover 66 may be a wheeledcart including floor-engaging wheels 68, brakes and/or adjustableleveling feet. When low-pressure turbine stage 40 is removed from theengine 10, aft portion of mid turbine frame 50 and aft ends oflow-pressure shaft 32 and high-pressure shaft 42 may be accessible.

Referring to FIGS. 3 to 8 , aircraft engine repair tool 60 (shown inFIG. 12 ) may include stabilizer 70, holder 72 and guide 74. As will bedescribed in detail below, stabilizer 70 may support shafts 32, 42 viasubstitute load path L2 defined between shafts 32, 42 and inner casing24. Load path L2 may be different from load path L1 provided by midturbine frame 50. Holder 72 may have an interface 76 attachable to themid turbine frame 50. Guide 74 may be movably engaged with shafts 32, 42and attached to holder 72. Guide 74 may guide movement of the holder 72and mid turbine frame 50 when attached to holder 72 relative to shafts32, 42 along the rotation axis R and may prevent movement of holder 72and mid turbine frame 50 relative to shafts 32, 42 transverse torotation axis R when mid turbine frame 50 is released from inner casing24.

Referring to FIGS. 3 to 7 , stabilizer 70 will be generally described.Stabilizer 70 may have a base 80 attachable to a forward structure ofengine 10. For example, base 80 may be attached to a forward structure82 (e.g., casing) of engine 10 (FIGS. 1 and 4 ). More particularly, base80 may have a three-prong, Y-shape configuration when viewed alongrotation axis R, and may include fasteners 84 connectable to attachmentpoints 84 a provided on forward structure 82 of engine 10 (FIG. 4 ).Base 80 may thus be disposed forward of shafts 32, 42. Base 80 mayfurther include a pivot 86 defining pivot axis 86 a. An arm 88 may bepivotally coupled to base 80 at pivot 86 and pivotable about pivot axis86 a.

Arm 88 may be sized and dimensioned to be inserted in a bore 90 ofhigh-pressure shaft 42 from a forward portion (end) of high-pressureshaft 42. In some embodiments, arm 88 may include a film 92 provided ona surface of arm 88 engaging bore 90 of high-pressure shaft 42. Film 92may be composed of relatively soft material(s) to protect bore 90 ofhigh-pressure shaft 42 when engaged by arm 88. Stabilizer 70 may furtherinclude actuator 94 for adjusting an angular position of arm 88 relativeto base 80 about pivot axis 86 a. In the present embodiment, actuator 94includes a screw 96 extending in a threaded hole 98 defined in arm 88.Screw 96 may be vertically offset from pivot axis 86 a. Upon selectiverotation of screw 96, screw 96 threadingly engages hole 98 and arm 88selectively pivots about pivot axis 86 a. In some embodiments, whenscrew 96 is tightened, an aft (i.e., distal) end of arm 88 is raisedalong arrow A in FIG. 4 , and an angular position of arm 88 relative tobase 80 about pivot axis 86 a can be selected. When arm 88 is raised andengages high pressure shaft 42, high-pressure shaft 42 may be movedupwardly. Conversely, when the aft end of arm 88 is lowered along arrowA in FIG. 4 , high-pressure shaft 42 may be moved downwardly and arm 88may disengage high pressure shaft 42. When high-pressure shaft 42 issupported by one or more bearings provided in bearing housing 52 of midturbine frame 50, a load supported by the one or more bearings can besupported by arm 88 as arm 88 is raised and engages high-pressure shaft42. In other words, arm 88 may selectively lift high-pressure shaft 42and define with base 80 at least a portion of substitute load path L2.Other types of actuators 94 (e.g. electromechanical actuator) could beused in other embodiments.

Referring to FIG. 5 , stabilizer 70 may further include gauge tool 100.Gauge tool 100 is adapted for insertion into bore 90 of high-pressureshaft 42 from aft portion of high-pressure shaft 42. Gauge tool 100 mayhave engagement portion 101 including expanders 101 a adapted forselectively engaging high-pressure shaft 42. Expanders 101 a may beselectively extended or retracted upon selective rotation of knob 101 b.When expanders 101 a are selectively extended for engaging high-pressureshaft 42, engagement portion 101 is centered in bore 90 of high-pressureshaft 42 and gauge tool 100 may be used to measure movement ofhigh-pressure shaft 42. Gauge tool 100 may include vertical movementdial indicator 102 a, and horizontal movement dial indicator 102 b. Dialindicators 102 a, 102 b may measure movement of high-pressure shaft 42along respective orientations. For instance, when high-pressure shaft 42is raised or lowered using base 80, arm 88 and actuator 94, verticalmovement dial indicator 102 a may measure vertical movement ofhigh-pressure shaft 42. Gauge tool 100 may also be adapted forengagement with guide 74 (FIG. 7 ).

Referring to FIGS. 6A, 6B and 13 , stabilizer 70 may further include oneor more support pins 110 attachable to inner casing 24. As best seen inFIG. 6A, each of the four support pins 110 includes a body 112attachable to inner casing 24, and a pin 114 selectively movablerelative to the body 112 using a knob 116. Each pin 114 extends throughholes defined in inner casing 24, and each pin 114 extend radially toabut compressor rotor 46 a of high-pressure compressor 46. Since thecompressor rotor 46 a is supported by high-pressure shaft 42, whensupport pins 110 are attached to inner casing 24 and their respectivepin 114 abuts compressor rotor 46 a, support pins 110 may assist inselecting and maintaining a position of high-pressure turbine stage 44and shafts 32, 42 relative to rotation axis R. Support pins 110 may alsobe used to center shafts 32, 42 horizontally and/or vertically when usedin conjunction with gauge tool 100. Support pins 110 may be attached toinner casing 24 to selectively abut compressor rotor 46 located in aftportion of high-pressure compressor 46. In addition and as schematicallyshown in FIG. 13 , support pins 110 may selectively define a portion ofload path L2 and support at least some of the load born by mid turbineframe 50. In other words, at least some of the load born by mid turbineframe 50 may be selectively born by support pins 110.

Referring to FIG. 13 , in some embodiments, stabilizer 70 may furtherinclude one or more shims 120 being insertable between inner casing 24and rotor 44 a of high-pressure turbine stage 44 of engine 10. The shims120 can be inserted in engine 10 from aft end 36 and through struts 56of mid turbine frame 50 before being disposed between inner casing 24and rotor 44 a. The thickness and number of shims 120 may be selected tofill a radial space between inner casing 24 and blade tips of rotor 44 aat one or more (e.g., three or more) locations. When disposed betweeninner casing 24 and rotor 44 a, shims 120 may also define a portion ofload path L2 (as schematically shown in FIG. 13 ). In some embodimentswhere one or more shims 120 are disposed between inner casing 24 androtor 44 a, the use of base 80, arm 88 and actuator 94 could be omittedto define load path L2. It is also contemplated that shims 120 could beused in conjunction with support pins 110 described above, and thus loadpath L2 between shafts 32, 42 and inner casing 24 could be defined byshims 120 and support pins 110.

Referring to FIG. 10 , interface 76 of holder 72 may have a generallycircular shape. Interface 76 may include one or more attachment points130 adapted for attachment to an aft portion of mid-turbine frame 50.

Referring to FIG. 11 , aircraft engine repair tool 60 may includeoptional extension frame 140 attachable to holder 72 between interface76 and machinery mover 66. Extension frame 140 may serve as an axialspacer for providing sufficient reach of attachment points 130 intoengine 10. In various situations, extension frames 140 of various sizesmay be used. Disassembly of engine 10 may thus be reduced for installingand/or removing mid turbine frame 50 using aircraft engine repair tool60 compared to other tools and techniques. Alternatively, no extensionframe 140 may be required in some situations.

Referring to FIGS. 8 and 9 , guide 74 may include insert 150 being sizedand dimensioned for insertion into radial gap 43 defined betweenlow-pressure shaft 32 and high-pressure shaft 42. Insert 150 may extendover low-pressure shaft 32 and may engage high-pressure shaft 42. Insert150 may also engage bearing housing 52 of mid turbine frame 50 andassist in supporting bearings within bearing housing 52 duringinstallation and/or removal of mid turbine frame 50 from engine 10.Guide 74 may further include one or more spokes 152 extending radiallyfrom hub 154. In the present embodiment, guide 74 has four spokes 152.Each spoke 152 may be attached to holder 72. Hub 154 defines acylindrical aperture 156 sized and dimensioned to receive insert 150therein. Guide 74 may further include plug 158. Plug 158 may bethreadingly connectable to aft portion of low-pressure shaft 32 (FIG. 12). Plug 158 may further have an outer portion 160 slidably engageable toinner wall 162 of insert 150. Length 170 of inner wall 162 may beselected to provide support to guide 74 and holder 72 over a desireddistance along rotation axis R. For example, length 170 may be selectedto be equal or greater than length 172 between bearing housing 52 andaft end of low-pressure shaft 32 so that mid turbine frame 50 may besupported by insert 150 until bearing housing 52 has cleared aft end oflow-pressure shaft 32. When mid turbine frame 50 is attached to holder72, spokes 152 are attached to holder 72, insert 150 extends through hub154, plug 158 is connected to low-pressure shaft 32 and insert 150extends within radial gap 43, guide 74 may guide movement of holder 72and mid turbine frame 50 relative to shafts 32, 42 along rotation axis Rand prevent movement of holder 72 and mid turbine frame 50 relative toshafts 32, 42 transverse to rotation axis R. Slidable engagement ofouter portion 160 of plug 158 with inner wall 162 of insert 150 mayfurther assist in preventing movement transverse to rotation axis R ofhub 154, spokes 152, holder 72 and mid turbine frame 50. In other words,guide 74 may allow movement of holder 72 and mid turbine frame 50 in adirection being parallel to rotation axis R while preventing holder 72and mid turbine frame 50 from moving in directions transverse torotation axis R. Such guided movement of holder 72 and mid turbine frame50 may assist in protecting seals and bearings within bearing housing 52during installation and/or removal of mid turbine frame 50.

FIG. 14 is a flowchart illustrating method 1000 for installing midturbine frame 50 on engine 10, or removing mid turbine frame 50 from theengine 10. Method 1000 may be performed using aircraft engine repairtool 60 as described above or some other tool(s). Aspects of method 1000may be combined with aspects of aircraft engine repair tool 60 and/orwith other methods and/or actions described herein. In variousembodiments, method 1000 may include: supporting shafts 32, 42 of engine10 via load path L2 between shafts 32, 42 and the support structure (inthe present embodiment, inner casing 24), load path L2 being differentfrom load path L1 (see block 1002); movably engaging guide 74 withshafts 32, 42 with guide 74 and attaching guide 74 to holder 72 so thatmovement of holder 72 relative to shafts 32, 42 along rotation axis R ispermitted and movement of holder 72 relative to shafts 32, 42 transverseto rotation axis R is prevented (see block 1004); with mid turbine frame50 attached to holder 72 and mid turbine frame 50 released from innercasing 24 of engine 10, moving holder 72 and mid turbine frame 50together along rotation axis R toward or away from an installed positionof mid turbine frame in inner casing 24 (see block 1006).

When mid turbine frame 50 is being moved toward the installed position,this may be indicative of mid turbine frame 50 being installed intoengine 10. Hence, after moving holder 72 and mid turbine frame 50 alongrotation axis R and toward the installed position (see block 1008), midturbine frame 50 may be attached to inner casing 24 (see block 1010).

When mid turbine frame 50 is being moved away from the installedposition, this may be indicative of mid turbine frame 50 being releasedfrom engine 10. Hence, after moving holder 72 and mid turbine frame 50along rotation axis R and away from the installed position (see block1012), mid turbine frame 50 may be removed from engine 10 (see block1014).

As explained above, engine 10 may be a turbofan gas turbine engine andmethod 1000 may further include removing turbine exhaust case 38 andlow-pressure turbine stage 40 from engine 10 before attaching holder 72to mid turbine frame 50. In some embodiments, depending on theconfiguration of engine 10 and on the type of mid turbine frame 50 beingattached to holder 72, other component(s) may need to be removed fromengine 10 to permit the removal or installation of mid turbine frame 50using aircraft engine repair tool 60. Accordingly, method 1000 mayinclude removing such components and reinstalling such components at theappropriate time.

Referring to FIGS. 4 to 13 , an illustrative scenario describing removalof mid turbine frame 50 using tool 60 will be described.

When turbine exhaust case 38 and low-pressure turbine stage 40 areremoved from engine 10, holder 72 is moved into position for attachmentto mid turbine frame 50 using attachment points 130. Spokes 152 of guide74 are attached to holder 72, insert 150 is inserted into radial gap 43.Insert 150 is then removed from radial gap 43. Gauge tool 100 isinserted into aft end of high-pressure shaft 42, expanders 101 a areselectively extended for engaging high-pressure shaft 42 and centeringengagement portion 101 inside bore 90, and dial indicators 102 a, 102 bare zeroed. At forward end 31 of engine 10, stabilizer 70 has arm 88inserted into bore 90 and base 80 is attached to forward structure 82using fasteners 84 and attachment points 84 a. Screw 96 is rotated toraise arm 88 upwardly such that arm 88 engages high-pressure shaft 42.Arm 88 is raised to lift shaft 42 until a maximum vertical travel on thegauge tool 100 is determined using dial indicator 102 a. Screw 96 isrotated to lower arm 88 downwardly and shaft 42 is again supported bymid turbine frame 50 via load path L1. A radial displacement value isdetermined from a value of maximum travel indicative of an amount ofplay available in the bearing supporting shaft 42. A selected radialdisplacement value may correspond to a mid point along the determinedmaximum vertical travel so as to correspond to a position where thebearing supporting shaft 42 is unloaded.

Support pins 110 are then attached to inner casing 24 and pins 114extend radially through inner casing 24 and remain spaced fromcompressor rotor 46 a.

Stabilizer 70 has screw 96 rotated to lift arm 88 until shaft 42 ismoved upwardly by the selected radial displacement value using dialindicator 102 a. Pins 114 are selectively extended using knobs 116 tomove high-pressure shaft 42 horizontally until the radial displacementvalue is reached using dial indicator 102 b. At this time, high-pressureshaft 42 is centralized in mid turbine frame 50 where the bearing(s)supporting high-pressure shaft 42 is/are unloaded and the load initiallyborn by mid turbine frame 50 is transferred to load path L2 provided bystabilizer 70 and support pins 110.

Expanders 101 a are retracted to disengage from high-pressure shaft 42.Gauge tool 100 is removed from aft end of high-pressure shaft 42. Insert150 is inserted back into radial gap 43. Plug 158 is threadinglyconnected to aft end of low-pressure shaft 32. Fasteners and bracketsattaching mid turbine frame 50 to inner casing 24 are removed forreleasing mid turbine frame 50 from inner casing 24. While leavingbypass duct 20 untouched, machinery mover 66 is moved into position toreach inside bypass duct 20 and attached to holder 72. Optionally,extension frame 64 a may be interconnected between machinery mover 66and holder 72. When holder 72 is attached to machinery mover 66,machinery mover 66 is moved in a direction parallel to rotation axis Raway from the installed position of the mid turbine frame 50 so as toremove mid turbine frame 50 from engine 10, as indicated by arrow 180.

In an alternative illustrative scenario, base 80 and arm 88 are omittedand one or more shims 120 are disposed between rotor 46 a and innercasing 24 to move high-pressure shaft 42 vertically. Support pins 110are then attached to inner casing 24 and pins 114 are selectivelyextended to move high-pressure shaft 42 horizontally. Gauge tool 100 mayoptionally be used to determine vertical and horizontal movement ofhigh-pressure shaft 42 and assist in centralizing high-pressure shaft 42within mid turbine frame 50. As shims 120 and support pins 110 defineload path L2, mid turbine frame 50 is unloaded and ready to be removedfrom engine 10 as described above.

The installation process is the reverse of the above-described removalprocess. During installation process, mid turbine frame 50 is attachedto holder 72 and supported by machinery mover 66. Arrow 182 indicatesthe mid turbine frame 50 being moved in a direction parallel to rotationaxis R toward the installed position using holder 72 and machinery mover66. When holder 72 and mid turbine frame 50 have been moved toward theinstalled position, mid turbine frame 50 may be attached to inner casing24.

The embodiments described in this document provide non-limiting examplesof possible implementations of the present technology. Upon review ofthe present disclosure, a person of ordinary skill in the art willrecognize that changes may be made to the embodiments described hereinwithout departing from the scope of the present technology.

1. An assembly comprising: a gas turbine engine including a mid turbineframe located between a first turbine rotor and a second turbine rotorin a turbine section of the gas turbine engine during operation of thegas turbine engine, the mid turbine frame being releasably attached to asupport structure within the gas turbine engine, the gas turbine engineincluding a shaft supporting the first turbine rotor, the mid turbineframe rotatably supporting the shaft relative to the support structureabout a rotation axis, the mid turbine frame defining a first load pathbetween the shaft and the support structure, the second turbine rotorbeing uninstalled from the gas turbine engine; and an aircraft enginerepair tool for installing and/or removing the mid turbine frame whenthe mid turbine frame is released from the support structure of the gasturbine engine, the aircraft engine repair tool including: a stabilizersupporting the shaft via a second load path between the shaft and thesupport structure, the second load path being different from the firstload path; a holder attached to the mid turbine frame; and a guidemovably engaged with the shaft and attached to the holder, the guidebeing configured to guide a movement of the holder and the mid turbineframe relative to the shaft along the rotation axis, and to prevent amovement of the holder and the mid turbine frame relative to the shafttransverse to the rotation axis when the mid turbine frame is releasedfrom the support structure.
 2. The assembly as defined in claim 1,wherein the stabilizer comprises: an arm inserted in a bore of theshaft; a base attached to the support structure of the gas turbineengine, the arm being pivotally coupled to the base about a pivot axis;an actuator for adjusting an angular position of the arm relative to thebase about the pivot axis; and the second load path being defined viathe arm engaging the shaft, and the base.
 3. The assembly as defined inclaim 2, wherein the gas turbine engine is a turbofan gas turbine enginehaving a forward end, and the base is disposed forward of the shaft. 4.The assembly as defined in claim 1, wherein the stabilizer comprises asupport pin extending between the support structure and a compressorrotor of the gas turbine engine supported by the shaft.
 5. The assemblyas defined in claim 1, wherein the stabilizer comprises a shim disposedbetween the support structure and the first turbine rotor of the gasturbine engine.
 6. The assembly as defined in claim 1, wherein theholder has an interface attached to an aft portion of the mid turbineframe.
 7. The assembly as defined in claim 1, comprising a machinerymover supporting the holder, and the holder being movable along therotation axis via the machinery mover.
 8. The assembly as defined inclaim 1, wherein the shaft comprises a first shaft supporting the firstturbine rotor and a second shaft supporting the second turbine rotor,the second shaft extends inside the first shaft, and the guide extendsover the second shaft and engages the first shaft. 9.-20. (canceled)